How are you authenticating to D2?  Do you have a trust configured?

If you have the exact same account name on both domains, each with the exact same password, you might still run into issues.  You might be better off (assuming you can't do a trust between domains) creating a local account on the agent computers and using that, as opposed to an account on either D1 or D2.

At any rate - authentication's your issue.

Domain controllers don't have local accounts though.

Tincan: I'd go with what MitchR is saying about having unique usernames in those domains and checking your trust, but I also assume that the account in domain D1 is in the Administrators group of domain D2? If not, do that. It should then work.

However, if you have to use 2 accounts, that's also an easy solution, and I use it on my side with no problems. Create an account: say, D1backup, and D2backup. Add D2backup into your service accounts list in Backup Exec on the backup server in question, and when you select a server, use the appropriate account.

I've sorted out the problem. I gave the Backup Exec account "logon as a batch job" rights on the DC's